NAS and arrays · bench log · ADR-2025-3653
Six Disks Out of the Box, and a Volume Reading RAW.
The NAS returned from a restart and the volume did not return with it. Six bays, 6 x 2TB drives running RAID 5
, and where the share had been there was now a partition listed as 'RAW' format
. He had read it correctly himself before he rang: the file system has become corrupted after being turned on
. What he asked for was the array put right or, failing that, the data taken off it — and what he wanted to know before anything else was whether he ought to let the box try to sort itself out.
Same story on yours? Tell us what it does — the look is free.
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What failed, and why.
RAW is not a description of the disks. It is what an operating system says when it can see a partition and cannot make sense of the structure within it, so it reports raw, unformatted space and offers to format that space — the most expensive button on the screen. Underneath, across six disks, everything is still where it was written. The clock on a job like this one is not ours; it belongs to the box. A NAS that comes up and finds its volume unreadable will often try to be helpful, with a consistency check or a resync or a rebuild onto a spare, and every one of those writes to the members while the structure above them is broken. The array does not improve while that runs. It gets harder to reconstruct. So the first thing asked of anybody in this position is to take the power off and leave the disks in their bays, in order.
What the bench did with it.
The order of the job →| Equipment used | Its work on this job | The reason for it |
|---|---|---|
| Atola TaskForce 2 | All six members copied side by side, so none of them waited on another | All members of a set copy at once, so no disk sits waiting on another |
| PC-3000 Portable PRO | Condition and firmware state checked on every one of the six before copying began | Manufacturer-level access to a disk, on a unit that sits beside the imagers |
| UFS Explorer RAID Recovery | Stripe order and parity rotation proved from the copies, then the file system repaired above them | Recovers the stripe order, then unpicks the volume manager the NAS layered above it |
What the bench did with it.
Copy all six before deciding anything
Nothing at all was analysed on the disks themselves. All six went onto the imager together, each read straight through, and every decision afterwards was taken against the copies. Put a six-member set through one channel at a time and a job of this size takes the better part of a week; run them side by side and the whole set is on the bench by the end of the day.
Prove each parameter rather than assuming any of them
Six disks give a large number of possible arrangements and only one of them is right. Bay order, stripe width and the direction in which parity rotates were each worked out from the copies and then tested against real directory structures already visible on the volume. A candidate that produces readable folders has been proved; one that merely matches what a given maker usually does has not. The array was assembled in software alone, so not a byte was written to any member at any stage.
Repair the file system that sits above the array
With the layout settled, the volume came up on the reconstructed array and the damage was exactly where he had said it would be: in the structures describing the file system, not in the data those structures point at. They were repaired on the copies. The tree was then walked from the top down, folder by folder, and files were opened rather than counted, because a file of the right size can still be a file of the wrong content.
What went home.
The volume reads again, and it went out on fresh media. All six original disks were returned untouched and still in their bay order. Not a byte was ever written to them, and the NAS was never asked to rebuild anything. Had it been allowed to, this would have been a longer entry with a worse ending.
Begin here if yours is doing the same thing.
Other RAID & NAS work on the log.
Yours doing something similar? Power it down first.
Prices are published and fixed. Memory cards and USB sticks are priced at £250 + VAT. A drive on its own comes to £300 + VAT. Anything holding a second disk, whether RAID, NAS or a server, opens at £500 + VAT. The first look costs nothing, and the figure that follows is fixed and in writing before a penny is charged. Switch it off and post it in. Most jobs carry no fee where no files return.